(1) Field of the Invention
The present invention relates to a medical valve apparatus comprising a valve seat and a movable valve membrane, which is valuable, for example, as an artificial valve apparatus of a pulsatile artificial heart or a pulsatile artificial heart-lung machine.
(2) Description of the Related Art
Recently, development of an artificial heart which exerts the function of the heart auxiliarily and temporarily outside the body at the time of a cardiotomy or other operations, has been developed. This artificial heart consists of a pulsatile blood pump device having a blood inlet port and a blood outlet port, and artificial check valves arranged in the blood inlet port and blood outlet port of this blood pump device to prevent a regurgitation.
A ball valve or a tilting disk valve is known as the artificial heart valve of this type. Namely, an artificial heart valve is known in which a ball or disk-shaped movable occluder is arranged in an opening of a sewn ring usually having a circular shape, and a frame-shaped strut is arranged outside the movable member to prevent dislocation of the movable occluder, wherein the movable member is fitted in the sewn ring upon closure of the valve to prevent a regurgitation, and the movable member moves in parallel or is tilted upon opening of the valve to form a blood passage.
Furthermore, a tricuspidal valve is known resembling a natural valve, which is composed of a natural tissue membrane or a polymer membrane, such as an Ionescu-shiley valve or a Carpentier-Edwards valve.
However, a valve of a clinical valve prosthesis is used as it is for this artificial heart, and accordingly, the cost is high. Particularly, in an artificial valve for an artificial heart, which is used for a relatively short time, and is then discarded the cost is very high. A thrombus is often formed in the gap between the valve ring and the inner wall of the inlet or outlet port of the blood pump device, and the valve is often broken by a water hammer phenomenon which is apt to occur due to pulsation of the fluid.
The tricuspidal valve has a complicated structure, and thus the manufacture is difficult and the cost is high. Furthermore, the tricuspidal valve made of a natural tissue has a problem of calcification in the living body, and in the case of a polymer tricuspidal valve, a thrombus is often formed on the root of the valve cusp.